This invention relates to a paying out device of the type comprising, in the direction of unwinding of a filament, at least one wire clamp, a return pulley, a brake pulley and a sliding pulley mounted on one end of a dynamometer arm. The other end of the arm has a graduated sector with means for positioning the point of attachment of one end of a dynamometer spring with the opposite end of the spring acting on a system for regulating the braking torque of the brake pulley in order to ensure automatic regulation of the tension of the filament on leaving the paying out device. All of these several elements are mounted on a support frame.
The invention relates more particularly to a paying out device for wires which is applicable to bobbin winding machines, paying out machines, cabling machines and, in general, all those apparatuses in which it is necessary to ensure constant tension of a known value on the filament during its unwinding. For the winding of a wire (for example, the winding of a motor or of an electrical transformer) to be carried out under a constant tension of the filament, it is necessary to exert on the latter a predetermined braking to give it the necessary tension.
Moreover, the paying out device of the present invention must also be satisfactory for starting up and stopping the winding. This regulation of the braking must remain satisfactory (and at the greatest possible speed) even if the winding to be carried out exerts pulses of a greater or lesser size.
Thus, for example, when a rectangular or polygonal casing is wound, the tension of the filament has a continuous component force (the only one, in the case of winding cylindrical casings) which is modulated by Pulses generated by the passage of edges, these pulses causing a break when the speed increases. On the other hand, to give a good output, the speed must be as great as possible.
Attempts to achieve both satisfactory braking and increased speed have been made with known devices such as is disclosed in French Pat. No. 76,577, British Pat. No. 1,317,042 and U.S. Pat. No. 3,707,269, all of the contents of which are incorporated herein by reference. All of these documents relate to a paying out device of the type described above. In this device, the tension of the filament is provided by the brake pulley, while the tension pulses generated by the winding are at best taken up by an oscillation of the dynamometer arm when it is in its working position. The correspondence of the tension of the filament to the braking force depends on the point of attachment of the spring, the tension of which is transmitted to the device for regulating the braking torque of the brake pulley 26.
Although this known type of paying out device functions in a satisfactory manner, it has constraints of positioning which can be awkward. Moreover, the control of the working position of the arm is not always convenient.
In the above mentioned constructions, the tension of the filament as a function of the rotation of the arm follows a sinusoidal pattern and, in the working position, the gradient is also considerable, and it would be desirable for this to be reduced in order that the regulated tension of the filament should change as little as possible when the arm is moved slightly away from its working position as a result of the pulses due to the winding to be carried out.